WordPress .org .com completely flexible/extendible fixed set of features need to purchase hosting free to sign up install/update WordPress yourself WordPress already installed/ updated many free plugins (extensions) some paid upgrades available
Username & password Don’t use admin Use a strong password https://strongpasswordgenerator.com/ Use a password manager like LastPass Or password memorising techniques
Avoid spam Discussion settings Turn off comments altogether if not needed Turn off comments after n days Stop Media Comment Spamming Akismet, Anti-spam
Image sizes At least as wide as your content (depends on theme) 1000px wide is usually a safe ballpark Optimise images without changing quality using programs like ImageOptim, Smush.it, ImageMagick WordPress also creates multiple image sizes (thumbnail, medium & large) for your use.